What are ASTM standards for medical face masks? Difference between ASTM level 1, 2, and 3 face masks

ASTM standard for medical face mask

What are ASTM standards for medical face masks? Difference between ASTM level 1, 2, and 3 face masks

If you are interested in knowing the ASTM standards for the medical masks, you must know ASTM F2100 – 21.

ASTM F2100 – 21

Standard Specification for Performance of Materials Used in Medical Face Masks

The Food and Drug Administration (FDA) refers to ASTM standards as the US endorsed standard for Medical Face MasksASTM F2100 specification outlines the performance requirements and test methods for medical face masks used in patient care and surgery.  Material performance for medical face masks is determined by testing for bacterial filter efficiency, differential pressure, and sub-micron particulate efficiency. It also considers resistance to penetration by artificial blood and flammability. 

Medical Face Mask Standards for USA and EU
Difference between ASTM level 1, 2, and 3 face masks

For EU market, please check out this article about EN 14683.  

Let’s take a detailed look at each area and its terminology.

1. BFE (Bacterial Filtration Efficiency).

BFE is a measurement of how well a medical face mask can filter out bacteria when exposed to a bacteria-containing aerosol.  ASTM recommends that the droplet containing Staph Aureus (average size 0.6-0.8 microns) be tested.  To be called a medical/surgical mask minimum of 95% filtration is required. High protection and moderate masks should have bacterial filtration rates of at least 98%.

To determine the BFE rating, some manufacturers use the Modified Greene & Vesley methodology. ASTM does not recommend this method for product comparisons or to evaluate consistency.

 

2. PFE  (Particle Filtration Efficiency)

PFE is a measure of how well a hospital mask filters submicron particles. It is used to predict that viruses will also be filtered in the same way. Higher percentages indicate better mask filtration. ASTM F2100 recommends that testing be done with particles sizes ranging from 0.1 to 5 microns.

It is important to compare test results by looking at the size of the particles.   Larger particles can lead to misleading PFE ratings.

 

3. Fluid Resistance:

Fluid resistance is the ability of the surgical mask to reduce fluid transfer from outer layers to inner layers as a result of splashes or sprays. ASTM recommends that fluid resistance be tested with synthetic blood at pressures 80, 120, and 160 mm Hg. This allows for the testing to determine if the mask is capable of minimizing fluid transfer from the outer layers to inner layers as a result of a splash or spray.

These pressures correspond to blood pressure:

  • 80mm Hg = vein pressure (Level 1) 
  • 120mm Hg = arterial pressures (Level 2);
  • 160mm Hg =Correlates with high pressures that could occur during trauma or surgery that includes high-pressure irrigation, such as orthopedics (Level 3).

 

4. Delta P (Pressure Differential)

Delta P is an objective measurement of airflow resistance and measures breathability. The Delta P-value is expressed in mm H2O/cm2. The more breathable the mask feels, the lower it will be. ASTM standards require that low barrier masks have a Delta P less than 6.0.

 

5. Spread the Flame:

Hospitals can contain heat, oxygen, and fuel so ASTM standards require flame resistance testing. All hospital masks must be able to resist flame exposure for at least three seconds.

6. ISO Certification:

All medical face masks must pass the above tests and be tested for skin sensitivity (ISO 10993-5, 10) to ensure they are safe. The material used in the construction of the mask comes in contact with the skin.

 

ASTM PROTECTION & INTENDED USAGE

LEVEL 1 (LOW) BARRIER:
80 mm Hg
LEVEL 2 (MODERATE) BARRIER:
120 mm Hg
LEVEL 3 (HIGH) BARRIER:
160 mm Hg
Light / minimum BFE & PFE protection High BFE & PFE protection High BFE & PFE protection
Used for general procedures and respiratory exam More breathable than high barrier mask
Designed to resist a splash or spray at venous pressure Designed to resist a splash or spray at arterial pressure Highest fluid resistance – designed to resist a splash or spray during tasks like orthopedic surgery or trauma

 

Reference:

  1. ASTM F2100 – 21 Standard Specification for Performance of Materials Used in Medical Face Masks. (n.d.). ASTM. Retrieved August 18, 2021, from https://www.astm.org/Standards/F2100.htm
  2. Bacterial & Viral Filtration Efficiency Tests. (n.d.). Nelson Labs. Retrieved August 18, 2021, from https://www.nelsonlabs.com/testing/bacterial-viral-filtration-efficiency-bfe-vfe/
  3. Particle Filtration Efficiency (PFE) Test | Nelson labs. (n.d.). Nelson Labs. Retrieved August 18, 2021, from https://www.nelsonlabs.com/testing/particle-filtration-efficiency-pfe/

 

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